
7/ 

La. 






MILK AND CREAM CONTESTS 



ERNEST KELLY 

In Charge of Market Milk Investigations, and 

GEORGE B. TAYLOR 

Market Milk Specialist, Dairy Division 




UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT CIRCULAR 53 



Contribution from the Bureau of Animal Industry 
JOHN R. MOHLER, Chief 



Washington, D. C. 



August, 1919 



WASHINGTON : GOVERNMENT PRINTINQ OFFICE : 1919 



^- 



MILK AND CREAM CONTESTS/ 



CONTENTS. 



Page. 

Contests promote better milk supplies 3 

Two kinds of contests 3 

Methods of scoring milk and cream 4 

Score card for milk 4 

Score card for cream 6 

Contests in which samples are prepared by 

contestants 8 

Preparation of samples 10 

Shipping the samples 10 

Handling samples at destination 10 



Page. 
Contests in which samples are taken ou the 

street 11 

Collecting the samples 12 

File card for recording milk scores 12 

Laboratory equipment for conducting con- 
tests 12 

Methods of analyzing and testing 14 

Publicity 25 



CONTESTS PROMOTE BETTER MILK SUPPLIES. 

FRIENDLY RIVALRY among milk producers and dealers is an 
important feature in the improvement of the milk supplies of 
cities. Any factor which encourages this rivalry must be given 
careful consideration by sanitarians and all milk authorities. Since 
the inauguration of milk and cream contests, in 1906, this method of 
promoting friendly rivalry has been recognized. At this time, be- 
sides State and National contests, a number of cities use such means 
for gradin.g milk supplies. 

Milk and cream contests promote competition among the dairy- 
men, lead to the gradmg of milk supplies, and through pubhcity 
encourage the efforts of producers as well as educate the consumers 
regarding the value of good milk and where the best can be obtained. 

TWO KINDS OF CONTESTS. 

Milk and cream contests are of two kinds — one in which the dairy- 
men prepare their own samples of milk or cream especially for the 
contest, the date of which is known; the other in which samples 
are collected on the street without the knowledge of the producers. 
The first method may or may not indicate the dairymen who gen- 
erally produce the higher grades of milk. It represents only care 
m the preparation of samples for definitely known contests. As an 
educational factor, however, it is very valuable, as it teaches pro- 
ducers care and cleanliness in the production and handling of milk. 
Of course, in such contests the dairymen take extraordinary care in 
the production and preparation of the samples, but there is neverthe- 
less an educational value, as shown by the fact that dairymen con- 
testing during several consecutive years usually receive higher scores 
each succeeding contest. In National and State contests all samples 

1 This circular is a revision of Department Bulletin 356. It is of interest to officials and sanitarians 
concerned in the control of milk supplies of cities and in a general way to producers of market milk. 

2 



r 






^-. 



X 



-^ 



IX 



Milk and Cream Contests. 



a 



are, of necessity, prepared samples. The advertising value of a high 
score is so great that much interest is always aroused. 

On the other hand the surprise contest, especially when it repre- 
sents samples of milk or cream covering a definite period of time, 
gives a mathematical rating to each producer based on his everyday 
product, thereby laymg the foundation for grading a city's milk sup- 
ply. Such contests are valuable in bettering the local milk supply 
and should be instituted especially in the smaller cities when labora- 
tory facilities are available. 

There are three classes of entries in milk and cream contests — cer- 
tified, raw market, and pasteurized. In grading, these classes must 
be regarded as entirely distinct, and in the report of results each class 
must be given separately. 

METHOD OF SCORING MILK AND CREAM. 

The samples are scored for bacteria, flavor and odor, sediment, fat, 
solids not fat (m case of milk), temperature or acidity (depending 
on the kind of contest), and the appearance of the bottle and cap. 
A perfect score is 100, divided as shown in the score cards following: 

[Front.] 

united states department of agriculture, 

Bureau of Animal Industry. 

dairy division. 



SCORE CARD FOR MILK. 



Place 

Class . 



Exhibit No. 



Exhibitor 
Address . . 



(Signed) 



Item. 


Perfect 
score. 


Score 
allowed. 


Remarks. 


Bacteria 


35 

15 
10 
15 
15 

1 ^ 

5 




Bacteria found per cubic centimeter 










Sediment 






Fat 












TeiBperalure (street samples) 




[Degrees, . 

i or 


or 


\oi(lit\* ^■nrpnflrecl samr>los^ 






Bottle and cap 


/Bottle, . 






\Cap, . 


Total 


100 













Date 



Judges. 

[OVEE}. 



4 Department Circular 53, U. S. Dept. of Agriculture. 



[Back.] 



DIRECTIONS FOR SCORING. 



Bacteria per Cubic Centimeter — Perfect Score, 35. 



Points. 

500 and under 35 

501-1,000 34. 9 

1,001-1,500 34. 8 

1,501-2,000 34. 7 

2,001-2,-500 34. 6 

2,501-3,000 34. 5 

3,001-3,-500 34. 4 

3,501-4,000 34. 3 

4,001-4,500 34. 2 

4,501-5,000 34. 

5,001-6,000 33. 8 

6,001-7,000 33. 6 

7,001-8,000 33. 4 

8,001-9,000 33. 2 

9,001-10,000 33. 

10,001-11,000 32. 8 

11,001-12,000 32. 6 

12,001-1.3,000 32. 4 

13,001-14,000 32. 2 

14,001-1.5,000 32. 

15,001-20,000 31 



Points. 

20,001-25,000 30 

25,001-30,000 29 

30,001-3.5,000 28 

35,001-40,000 27 

40,001-4.5,000 26 

4.5,001-50,000 25 

50,001-.5.5,000 24 

55,001-60,000 23 

60,001-65,000 22 

65,001-70,000 21 

70,001-75,000 20 

75,001-80,000 19 

80,001-8.5,000 IS 

85,001-90,000 17 

90,001-95,000 16 

95,001-100,000 15 

100,001-120,000 12. 5 

120,001-140,000 10. 

140,001-160,000 7. 5 

160,001-180,000 5. 

180,001-200,000 2. 5 

Above 200,000 



Note. — When the number of bacteria per cubic centimeter exceeds the local legal limit the score shall 
beO. 

Plavor .\nd Odor — Perfect Score, 15. 

Deductions for disagreeable or foreign odor or flavor should be made according to conditions foimd. 
When possible to recognize the cause, it should be described under " Remarks." 

Sediment — Perfect Score, 10. 

Examination for sedunent may be made by means of a sediment tester and the resulting cotton disks 
compared with standards; or the sediment may be determined by examination of the bottom of the milk 
in the bottle. In the latter case the milk should stand undisturbed for at least an hour before tlie exami- 
nation. Raise the bottle carefully in its natural upright position until higher than the head. Tip slightly 
and observe the bottom of the milk with the naked eye or by the aid of a reading glass. The presence of 
the slightest movable speck makes a perfect score impossible. Further deductions should be made ac- 
cording to the amoimt of dirt found. AVhen possible, the nature of the dirt should be described under 
"Remarks." 

Fat in Milk— Perfect Score, 15. 



Points. 

4.0 per cent and over 15 

3.9 per cent 14 

3.8 per cent 13 

3.7 per cent 12 

3.6 percent 11 

3.5 percent 10 

3.4 per cent 9 i 

Note. — When the per cent of fat is less tlian the local legal limit the score shall be 0. 

Solids Not Fat— Perfect Score, 15. 
Points. 

8.7 per cent and over 15 

8.6 per cent 13 

8.5 per cent 11 

8.4 per cent 9 

8.3 per cent 7 

Note. — When the per cent of solids not fat is less than the local legal limit the score shall be 
Temperature (Street Samples)— Perfect Score, 5. 
Points. 

50° F. or below 5 

5110 53° 4 

54 to 56° 3 



I'oiiils. 

3.3 per cent 8 

3.2 per cent 7 

3.1 per conl 5 

3.0 per cent 3 

2.9 per cent 1 

Less than 2.9 per cent 



Points. 

8.2 per cent 5 

8.1 percent 3 

8 per cent 1 

Less than 8 per cent 



57 to 60°.. 
Above 60° 



Points. 
.... 1 
.... 



Milk and Cream Contests. 



iVi 



[ISark— ('(intinueil.] 
AciDiT-^- (Pkkpakei) Samples)— Perfect Scoke, 5 
I'oinis 



0.2 per cent or less .'> 

0.21 per cent 4 

0.22 per cent .3 



Point."!. 

0.23 per cent 2 

0.24 per cent 1 

More than 0.24 per cent 



Hottle A.vn Cap— Perfect Score, 5. 

Peductions in .score .sluniltl he made for dirty or chipped bottles or for cap.s which do not cover the 
lips of tlie bottles or do not fit i)roperly in the cap seats. 



I Front.) 
UNITED STATES DEPARTMENT OF AGRICULTURE, 

Bureau of Animal Industry, 
haiky Dn^isioN. 

SCORE CARD FOR CREAM. 



Place 

Class Exhibit No. 



Item. 



Bacteria. 



Flavor and odor . 

Sediment 

Fat 



Temperature (street .samples). 

or 
Acidit y ( prejiared .samples). . . 
BotI le and cap 



Total. 



Perfect 
score. 



3.5 

2.") 
II) 
20 



J 00 



Score, 
allowed. 



Remarks. 



Bacteria found \)ot culiic centime- 
ter 

Cowy, l)itter, feed, flat, strong 



Per cent. 
Degrees. . 

or 
Per cent . 

Cap 

Bottle... 



Exhil)itor 
Address.. 



(Signed). 



Date. 



Judges. 

tovEi:. 



6 Department Circular 53, U. S. Dept. of Agriculture. 



[Back.] 
directions for scoring. 
Bacteria pee Cubic Centimeter— Perfect Score, 35, 
Points. 



Under 500 35 

501-1 ,000 34. 9 

1 ,001-1 ,500 34. 8 

1 ,501-2,000 34. 7 

2,001-2,500 34. 6 

2,501-3,000 34. 5 

3,001-3 ,500 34. 4 

3 ,501-4 ,000 34. 3 

4,001-4,500 34. 2 

4,501-5,000 34 

5,001-6,000 33. 8 

6,001-7,000 33. 6 

7,001-8,000 33. 4 

8,001-9,000 33. 2 

9,001-10,000 33 

10,001-11 ,000 32. 8 

11,001-12,000 32. 6 

12,001-13,000 32.4 

13,001-14,000 32. 2 

14,001-15,000 32 

15,001-20,000 31 



Points. 

25,001-30,000 29 

30,001-35,000 2S 

35,001-40,000 27 

40,001-45,000 26 

45,001-50,000 25 

50,001-55,000 24 

55,001-60,000 23 

60,001-65,000 22 

65,001-70,000 21 

70,001-75,000 20 

75,001-80,000 19 

80,001-85,000. 18 

85,001-90,000 17 

90,001-95,000 16 

95,001-100,000 15 

100,001-120,000 12. 5 

120,001-140,000 10 

140,001-160,000 7.5 

160,001-180,000 5 

180,001-200,000 2. 5 

Above 200,000 



20,001-25,000 30 

Note.— When the number of bacteria per cubic centimeter exceeds the local legal limit, the score shall 

be 0. „ . 

Fl.\.vor and Odor— Perfect Score, 2a. 

Deductions for disagreeable or foreign odor or flavor should be made according to conditions found. 
When possible to recognize the cause, it should be described under "RemarliS." 

Sediment— Perfect Score, 10. 

E-xamination for sediment should be made only after the cream has stood for at least an hour undisturbed 
in any way. Raise the bottle carefully in its natural upright position, until higher than the head. Tip 
slightly and observe the bottom of the cream with the naked eye or by the aid of a reading glass. The 
presence of the slightest movable speck makes a perfect score impossible. Further deductions should be 
made according to the amount of dirt found. When possible the nature of the dirt should be described 
tmder " Remarks." 

Fat in Cream— Perfect Score, 20. 



Points. 

25 per cent or above 20 

24 per cent 19. 5 

23 per cent 19 

22 per cent 18. 5 

21 per cent 18 



Points. 

19 percent 17 

18 percent , 16 

17 percent 12 

16 percent 8 

15 per cent 4 

Less than 15 per cent 



20 per cent 17.5 

Note.— When the per cent of fat is less than the local legal limit the score shall l>e 
Temperature (Street Samples)— Perfect Score, 5. 



Points. 

50 degrees F. or below 5 

51 to 53 4 

54 to 56 3 



Points. 

57 to 60 1 

Above 60 



Acidity (Prep.4.red Samples) — Perfect Score, 5. 

Points. 

0.23 per cent 2 

0.24 per cent 1 

More than 0.24 per cent 



Points. 

0.2 per cent and less 5 

0.21 per cent 4 

0.22 per cent 3 



Bottle and Cap — Perfect Score, 5. 
Deductions in score should be made for dirty, chipped bottles; for caps which do not cover the lips of the 
bottles or do not fit properly in the cap seats. 



Milk and Cream Contests. 7 

CONTESTS IN WHICH SAMPLES ARE PREPARED BY CONTESTANTS. 

Before definitely announcing tlie time and details for holding 
milk and cream contests, the persons in charge should arrange to 
obtain prizes for the contestants. This is important, since there 
should be an additional incentive for the producers besides the 
desire of winning the contests. In local contests such city organiza- 
tions as the Chaml)er of Commerce, the Rotary Club, civic leagues, 
or women's clubs might be interested in furnisliing prizes, such as 
money, cups, or even dairy equipment. Interested commercial 
fimis may easily be persuaded to give prizes. 

After details of the contest are arranged, general publicity can 
be given tlu'ough local newspapers. It is best, however, not to 
depend too much upon this kind of publicity but to send preliminary 
notices to the dairymen themselves, as a great deal of individual 
effort usually is needed in interesting the producers. Each pro- 
spective contestant should receive an entry blank, the filling out and 
sending in of which must be made prerequisite to the entering of 
samples of milk or cream in the contest. 

SAMPLE ENTRY BLAXK. 
depaktmext of health. 

City of 

official entry blank. 

MILK AND (REAM CONTEST. 

Held at from to 

(Place.) 
Under the direction of 

The following classes are provided: 
Class I. Raw market milk. 
Class II. Certified milk. 
Class III. Pasteurized market milk. 
Class IV. Raw market cream. 
Class V. Pasteurized market cream. 

RULES. 

1. Competition is open to all milk and cream producers and distributors supply- 

ing milk and cream to 

2. Only one entry may be made in any one class. 

3. Producers of certified milk are barred from competition in any other class. 

4. All samples of certified milk must be accompanied with a certificate issued by the 

medical milk commission under whose super^•ision the milk is produced. 

5. Entries in milk classes consist of 4 pints of milk in pint bottles. 

6. Entries in cream classes consist of 4 one-half pints of cream in half-pint bottles. 

7. All entries of milk and cream after scoring become the property of the depart- 

ment of health of 

8. No contestant will be entitled to placing who does not make answer to each 

question herein given, sign declaration and forward this official entry blank 

to , 

(Name.) (Address.) 



8 Department Circular 53, U. S. Dept. of Agriculture. 

HOW TO COMPETK. 

Milk or cream to compete in this contest must be delivered or shipped, prepaid, to 



In" order that all milk and cream entered by contestants may be of the same age 

when scored, all samples must be produced or prepared on 

(Date.) 
and shipped immediately. Bottles should be carefully packed in ice in a proper 
shipping box, and this box marked plainly on the inside cover as well as on the out- 
side with the owner's name and address. 

An official representative of the judges will receive all samples and place them at 
once in cold storage. 

APPLICATION AND QUESTIONS TO BE ANSWERED. 

Please enter for me four (pint) bottles of to com- 

(§ pint) 

pete in class in accordance with conditions herein 

prescribed. 

FOR CLASSES I, II, AND IV. 

1. On what day and hour was the sample entered in this contest drawn? 

2. How many cows contributed to the sample of milk entered? 

3. What kind and quality of feed was given cows daily during the week preceding 

the production of the sample? 

4. How were cows cleaned previous to milking? 



5. AVhat kind of pail was used, small-top or open? 

6. How were the utensils sterilized? 



7. What method of straining was used? 

8. How was the milk cooled? 

How long after milking? To what temperature? 

9. Have you previously exhibited milk or cream at any local. State, or National show 

10. (Additional for cream). How was the sample separated? 

How was the separator cleaned? 



11. (Additional for certified.) Give name and address of medical milk commission 
certifying to your product 

FOR CLASSES HI AND V. 



12. When was the sample pasteurized? 

13. What was the average age of the product at the time of pasteurization?. 



14. Did you use a clarifier? 

15. To what temperature was the product heated? 

16. How long was it held at that temperature? 

17. Do you use automatic temperature control and recording thermometers? 



18. To what temperature was the product cooled? 

19. How was the pasteurizing apparatus cleaned? 



I, , do hereby declare each and every statement 

in answer to the foregoing questions to be true. I do furthermore declare that the 
product submitted by me is the pure natural product, free from preservatives, and 
(for Classes I, II, and IV) that it has not been heated or changed in any way. 

Date (Name) 

(Address) 

Do you wish shipping box returned 
at your expense? 



Milk and Cream Contests. 9 

PREPARATION OF SAMPLES. 

The person in charge of the contest should issue detailed instruc- 
tions regarding packing and delivery. Express charges should be 
paid by consignor. Contests with prepared samples would be 
fairer and results more valuable if the sample represented the milk 
of the entire herd. In some contests this is required. Generally, 
however, entries representmg the product of one or more cows may 
be furnished. Usually great care is taken to obtain the sample 
under as near sterile conditions as possible. Thorough washing of 
the udder and the hands of the milker is necessary, and a properly 
sterilized, small-top pail should be used. Sterile absorbent cotton or 
filter cloth is the best material to use for straining milk. 

It is not advisable to pour the milk, while still warm, mto the final 
container, as the shrinkage when cold leaves some space between 
the milk and the cap. This may detract from the appearance of 
the bottle, and churning may result. It is suggested that the milk 
be stramed mto a sterile contamer and cooled, special care being 
taken to avoid contamination. The milk, after mixing, may then 
be poured into sterile phit bottles and the caps put on. Caps may 
be sterilized by dipphig into melted paraffin, but care should be 
taken not to heat the paraffin too much, as it gives off odors at high 
temperatures. Wlien the cap is placed firmly into the cap seat of 
the bottle, some melted paraffin may be poured on. The top of the 
bottle should be protected by means of a cap cover. When filled 
and capped the bottles must be packed immediately m ice and kept 
cold but not frozen, until ready for examination. An ice-and-salt 
mixture for cooling should nev(n* be used, as it may freeze the 
samples. 

SHIPPING THE SAMPLES. 

If the samples are to be shipped, special care must be taken in 
labeling and packing. In local contests the contestants usually 
bring in their own samples, properly iced, but when shipping is neces- 
sary great care should be taken to pack the samples so that they 
will remain cold and there will be no breakage. One method is to 
place the samples m a small, close-fitting contamer, which, in turn, 
is securel}' fastened in an insulated box containmg cracked ice. The 
outer box may be insulated with cork or sawdust. The owner's 
name and address should be plainly written on the inside of the 
cover of the outer box. The package must be plainly addressed on 
the outside to the consignee and bear the sender's name and address. 

HANDLING SAMPLES AT DESTINATION. 

As soon as received at the place where the contest is to be held 
the sample should be put into cold storage at a temperature between 
35° and 40° F. until ready for exammation. When the shipping 

122545°— 19 2 



10 Department Circular 53, U. S. Dept. of Agriculture. 

boxes are opened the name and address of the consignee (producer) 
are taken and each of the bottles tagged with its class and number. 
The name of the contestant, the class of the product, and the number 
given are placed m an envelope and the envelope sealed. On the 
outside of this sealed envelope the number of the sample and the 
class are placed. The person in charge of the contest should keep 
the records, and it is desirable for the judges to know the samples 
only by numbers. 

As there are four bottles in each entry one may be used for chem- 
ical analysis; one for bacteriological examination and sediment; one 
for judging flavor, odor, and appearance; and one held ui reserve to 
be placed on exhibition. This method may be varied to meet special 
conditions. 

Tlie best sample in each class must be declared the winner of that 

class, provided, of course, that all conditions have been complied 

with. In case of ties in the total score, the entry having the lowest 

bacteria count should outrank the others. Samples of high merit 

that have not won a prize may be awarded a diploma or cerfificate 

bearing the seal of the health department. The following form may 

be used: 

DIPLOMA OF MERIT. 

The Health Department 

of the City of 

Awards a Diploma of Merit 
to 



For a sample of scoring , exhibit a% 

the held at 



Judges: 



(Signed) 

[seal.] Superintendent of Contest. 

Tlie persons in charge of the contest should furnish contestants 
with detailed copies of their scores, and be ready to answer questions 
regarding them. As the prmcipal reason for holding the contests is 
to improve the milk supply, authorities should take advantage of the 
data furnished by dairymen to point out faults in the production and 
handling of the milk or cream and advise ways to improve the quality. 

CONTESTS IN WfflCH SAMPLES ARE TAKEN ON THE STREET. 

Tliis method of conducting milk contests, if properly carried out, 
furnishes a basis for grading the milk supply of cities. As in the 
contests with prepared samples, the three classes — pasteurized and 
raw market milk and cream and certified milk — must be kept separate. 



Milk and Cream Contests. 



11 



COLLECTING THE SAMPLES. 

At least once a month, and oftener if possible, the health depart- 
ment should collect 2 pint bottles of milk and 2 half-pint bottles of 
cream from each person delivering milk or cream in the city. At 
the time of coUectiou one of the samples should be well mixed, the 
bottle opened, and the temperature of the milk or cream taken. This 
sample should be properly marked so as not to be used for bacterio- 
logical examination, but used later for chemical determinations. 
Both samples should be placed immediately in ice until ready for 
analysis. The following detenninations are made: Bacteria, sedi- 
ment, specific gravity, fat, solids not fat, flavor and odor, and con- 
dition of bottle and cap. 

Careful records of the determinations as well as the temperature 
of the milk or cream at time of collection should be made and prop- 
erly filed. 

FILE CARD FOR RECORDING MILK SCORES. 

Name of dairy Claaa 

Name of owner 

Place P. O. address 



Date 
sample 
taken. 


Bacte- 
ria per 
cubic 
centi- 
meter. 


Flavor and odor 
score and remarks. 


Sedi- 
ment 
score. 


Specific 

gravity 

at 00° 

F. 


Fat. 


Solids 
not fat. 


Tem- 
pera- 
ture 
on 
street. 

De- 
grees F. 


Bottle 
and 
cap 

score. 


Remarks. 












Per cent. 


Per cent. 






















1 








'""/.'.'.\'.'.'.'..'... 




































i 













After a definite period of time — for example, 3, 6, or 12 months — 
the determinations made on the samples of each dairyman are aver- 
aged; these averages constitute a new record which is transferred 
to the milk or cream card and scored. The scores allowed each 
point are added together to make the total score. At the end of 
the period the names of the dairymen are pubhshed m the order of 
their scores, the highest in each class commg first. 

For the purpose of grading, the dairymen of each class scoring 
above 90 may be put in the same grade; those scoring between 80 
and 90 in another grade; and those scoring below 80 in another, 
thus making thi-ee grades in each class. 

LABORATORY EQUIPMENT FOR CONDUCTING CONTESTS. 

It is evident that the health department of a city must have proper 
laboratory equipment in order to conduct milk and cream contests. 
The following is a guide for the equipment of an average laboratory 
for doing such work. Quantities of the supplies may be varied 
according to the amount of work to be done. 



12 Department Circular 53, 11. S. Dept. of Agriculture. 

CHEMICAL EQUIPMENT, 

Babcock milk tester, 8 to 24 bottles, for fat determinations. 

Westphal Ijalance or accurate lactometer with cylinder for specific gravity deter- 
mination. 

Milk-test bottles, 8 per cent, for fat in milk. 

Cream-test Iwttles, 9 grams, 50 per cent, for fat in cream. 

Cream-test scales for weighing cream. 

Pair dividers. 

Pipettes, 17. G culnc centimeters, for measuring milk or acid. 

Combined acid ]>ottle and pipette. 

Burette, 50 cul>ic centimeters, glass stopcock, graduated in tenths, for acidity deter- 
mination. 

Glass stirring rods for acidity determination. 

Burette holder. 

Beakers, 100 cul)ic centimeters, for flavor and odor and acidity. 

Sediment tester for dirt in milk. 

Cotton disks f(»r sediment. 

Fahrenheit dairy thermometers for temperature of samples on collection. 

Bunsen burners, gas, with rubber tubing. 

Commercial sulphuric acid for fat determination. 

Sodium hydroxid, tenth-normal solution, for acidity. 

Phenolphthalein indicator for acidity determination. 

BACTERIOLOGICAL EQUIPMENT. 

Autoclav, medium size, for steam sterilization. 
Sterilizing oven for dry-air sterilization. 
Incubator, for growing Ijacteria. 
Water bath for melting agar tubes. 
For preparation of media: 

Balance, with weights to 5 kilos. 

Double boiler, one-half gallon. 

Funnel glass, 6 inches in diameter. 

Burette, 50 cubic centimeters, glass stopcock, graduated in tenths. 

Gas stove, single burner. 
1-cubic centimeter pipettes to deliver between 2 marks, graduated in tenths with 

extra tenth above mark, for measuring dilutions. 
Test tubes, lipless, for holding 10 cubic centimeters media. 
Test-tube baskets. 
For measuring liquids : 

5 cubic centimeter pipette. 

10 cubic centimeter pipette. 

25 cubic centimeter pipette . 

50 cubic centimeter pipette. 

100 cubic centimeter cylinder, graduated. 

500 cubic centimeter cylinder, graduated. 

1,000 culjic centimeter cylinder, graduated. 
Petri dishes for plating samples. 
Glass bottles, 8-ounce, for sterile dilution water. 

Thermometer ( — 10° to -f 110° C.) for temperatures in laboratory operations. 
Thermometer (-10° to -|-200° C.) for dry-air ovens. 
Pipette boxes, copper orgalvanized iron, for holding 1-cubic centimeter pipettes. 



Milk and Cream Contests. 



13 



For counting bacteria: 

Reading glass, 4-inch, 21- magnifications. 

Counting plate. 

Tally machine. 

Wax pencil. 
Al)sorbent cotton for filtering media. 
Nonabsorbent cotton for plugging test tubes. 
Canton flannel for filtering media. 
For making media: 

Peptone; beef extract; agar, shredded. 
For adjusting media: 

Sodium hydroxid, normal. 

Sodium hydroxid, tenth normal. 

Hydrochloric acid, tenth normal. 

Phenolphthalein indicator. 

METHODS OF' ANALYZING AND TESTING. 

It is of special importance in all analytical work that the standard 
methods prescribed be followed. No attempt is made here to give 
details of milk analysis, as every laboratory equipped to do this kind 




Fig. 1.— VVestplial balance and lactometer far determining specific gravity of milk. 

of work must certainly contain the proper reference books. Besides 
the usual books found in all health or food laboratories the analyst 
should have the following pamphlets: 

Chemical Testing of Milk and Cream, Bureau of Animal Industry, liCaflet A 12, 
U. S. Department of Agricidture, Washington, D. C. 

Official and Pro-sasional ^Methods of Analysis, Association of Official Agricultural 
Chemists, Bvueau of Chemistry Bulletin 107, Revised. JJ. S. Department of Agricul- 
tme, Washington, D. C. 

Testing IMilk and Cream for Butterfat, Circular 78, Purdue University Agricidtural 
Experiment Station, l.a l*'ayette, Ind. 



14 Department Circular 53, U. S. Dept. of Agriculture. 

Standard Methods of Bacteriological Analysis of ]\Iilk, Pro\'isional Report of the 
Laboratory Section of the American Public Health Association, 126 Massachusetts 
Avenue, Boston, Mass. 

SPECIFIC GRAVITY. 

The determination of specific gravity should be made either by a 
Westphal balance or by an accurately graduated lactometer. (Fig. 1 .) 
Tlie importance of accuracy in taking the specific gravity is better un- 
derstood when it is realized that from the specific gravity and the fat 
found, the total solids or solids not fat are calculated. As most of 
the lactometers are standardized to 60° F. (15° C), it is important 
that the temperature of the milk to be tested should closely approxi- 
mate this temperature. If it is necessary to take the readings at 
some other temperature, the following table of correction, by Dr. 
Paul Vieth, should be used. 



Table for correcting the specified gravity of milk according 


to temperature. 




Degrees of lac- 


Degrees of thermometer (Fahrenheit). 


tometer. 


45 


46 


47 


48 


49 


50 


51 


52 


53 


54 


55 


56 


57 


58 


59 


60 


20 


19.0 
19.9 
20.9 
21.9 
22.9 
23.8 
24.8 
25.8 
26.7 
27.7 
28.6 
29.5 
30.4 
31.3 
32.2 
33.0 


19.0 
20.0 
21.0 
22.0 
22.9 
23.9 
24.9 
25.9 
26.8 
27.8 
28.7 
29.6 
30.5 
31.4 
32.3 
33.1 


19.1 
20.0 
21.0 
22.0 
23.0 
24.0 
24.9 
25.9 
26.8 
27.8 
28.7 
29.6 
30.5 
31.4 
32.3 
33.2 


19.1 
20.1 
21.1 
22.1 
23.1 
24.0 
25.0 
26.0 
26.9 
27.9 
28.8 
29.7 
30.6 
31.5 
32.4 
33.4 


19.2 
20.2 
21.2 
22.2 
23.2 
24.1 
25.1 
26.1 
27.0 
28.0 
28.9 
29.8 
30.7 
31.6 
32.5 
33.5 


19.2 
20.3 
21.2 
22.2 
23.2 
24.1 
25.1 
26.1 
27.0 
28.0 
29.0 
29.9 
30.9 
31.8 
32.7 
33.6 


19.3 
20.3 
21.3 
22.3 
23.3 
24.2 
25.2 
26.2 
27.1 
28.1 
29.1 
30.0 
31.0 
31.9 
32.9 
33.8 


19.4 
20.3 
21.3 
22.3 
23.3 
24.3 
25.2 
26.2 
27.2 
28.2 
29.1 
30.1 
31.1 
32.0 
33.0 
33.9 


19.4 
20.4 
21.4 
22.4 
23.4 
24.4 
25.3 
26.3 
27.3 
28.3 
29.2 
30.2 
31.2 
32.1 
33.1 
34.0 


19.5 
20.5 
21.5 
22.5 
23.5 
24.5 
25.4 
26.4 
27.4 
28.4 
29.3 
30.3 
31.3 
32.3 
33.2 
34.2 


19.6 
20.6 
21.6 
22.6 
23.6 
24.6 
25.5 
26.5 
27.5 
28.5 
29.4 
30.4 
31.4 
32.4 
33.3 
34.3 


19.7 
20.7 
21.7 
22.7 
23.6 
24.6 
25.6 
26.6 
27.6 
28.6 
29.6 
30.5 
31.5 
32.5 
33.5 
34.5 


19.8 
20.8 
21.8 
22.8 
23.7 
24.7 
25.7 
26.7 
27.7 
28.7 
29.7 
30.6 
31.6 
32.6 
33.6 
34.6 


19.9 
20.9 
21.9 
22.8 
23.8 
24.8 
25.8 
26.8 
27.8 
28.8 
29.8 
30.8 
31.7 
32.7 
33.7 
34.7 


19.9 
20.9 
21.9 
22.9 
23.9 
24.9 
25.9 
26.9 
27.9 
28.9 
29.9 
30.9 
31.9 
32.9 
33.9 
34.9 




21 




22 

23 




24 




25 




26 




27 

28 

29 


. 


30 

31 




32 




33 




34 




35 









Degrees of lactometer. 



20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 



Degrees of thermometer. 



61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 



20.1 
21.1 
22.1 
23.1 
24.1 
25.1 
26.1 
27.1 
28.1 
29.1 
30.1 
31.2 
32.2 
.33.2 
34.2 
35.2 



20.2 
21.2 
22.2 
23.2 
24.2 
25.2 
26.2 
27.3 
28.3 
29.3 
30.3 
31.3 
32.3 
33.3 
34.3 
35.3 



20.2 
21.3 
22.3 
23.3 
24.3 
25.3 
26.3 
27.4 
28.4 
29.4 
30.4 
31.4 
32.5 
33.5 
34.5 
35.5 



20.3 
21.4 
22.4 
23.4 
24.4 
25.4 
26.5 
27.5 
28.5 
29.5 
30.5 
31.5 
32.6 
33.6 
34.6 
35.6 



20.4 
21.5 
22.5 
23.5 
24.5 
25.5 
26.6 
27.6 
28.6 
29.6 
30.7 
31.7 
32.7 
33.8 
34.8 
35.8 



20.5 
21.6 
22.6 
23.6 
24.6 
25.6 
26.7 
27.7 
28.7 
29.8 
30.8 
31.7 
32.9 
33.9 
34.9 
35.9 



20.6 
21.7 
22.7 
23.7 
24.7 
25.7 
26.8 
27.8 
28.8 
29.9 
30.9 
31.8 
33.0 
34.0 
35.0 
36.1 



20.7 
21.8 
22.8 
23.8 
24.9 
25.9 
27.0 
28.0 
29.0 
30.1 
31.1 
32.0 
33.2 
34.2 
35.2 
36.2 



20.9 
22.0 
23.0 
24.0 
25.0 
26.0 
27.1 
28.1 
29.1 
30.2 
31.2 
32.2 
33.3 
34.3 
35.3 
36.4 



21.0 
22.1 
23.1 
24.1 
25.1 
26.1 
27.2 
2S.2 
29.2 
30.3 
31.3 
32.4 
33.4 
34.5 
35.5 
36.5 



21.1 

22.2 
23.2 
24.2 
25.2 
26.2 
27.3 
28.3 
29.4 
30.4 
31.5 
32.5 
33.6 
34.6 
35.6 
36.7 



21.2 
22.3 
23.3 
24.3 
25.3 
26.4 
27.4 
2S.4 
29.5 
30.5 
31.6 
32.6 
33.7 
34.7 
35.8 
36.8 



21.3 
22.4 
23.4 
24.4 
25.5 
26.5 
27.5 
28.6 
29.7 
30.7 
31.8 
32.8 
33.9 
34.9 
36.0 
37.0 



21.5 
22.5 
23.5 
24.6 
25.6 
26.6 
27.7 
28.7 
29.8 
30.9 
31.9 
33.0 
34.0 
35.1 
36.1 
37.2 



21.6 
22.6 
23.7 
24.7 
25.7 
26.8 
27.8 
28.9 
29.9 
31.0 
32.1 
33.1 
34.2 
35.2 
36.3 
37.3 



The milk to be tested for specific gravity should be well mixed 
either by gently inverting the bottle several times or by pouring 
back and forth from the bottle to a beaker. In mixing the milk, as 



Milk and Cream Contests. 



15 



well as in pouring into a cylinder for the determination of the specific 
gravity, care should be taken to avoid the formation of air bubbles. 
In using the lactometer a meniscus is formed at the point where 
the stem comes in contact with the milk. The point to be read is at 
the actual surface of the liquid and not at the top of the meniscus. 

MILKFAT (BUTTERFAT). 

In order to distribute the fat evenly the bottle of milk or cream 
must be well mixed, preferably by pouring back and forth from the 
bottle to a beaker. This should be done just before the product for 
analysis is measured out. The charge of milk consists of 17.6 cubic 
centimeters and is measured; the cream charge consists of 9 or 18 
grams and is always weighed. 





/-I 




' ~-r 


A. 


^^—e 


c- 


E— 5 




=— <t 




^J 




^^—z 


n 


— 




^— / 




"~ 


\ 






a 

<<5 
/rf 
/J 
12 
ii 
/O 

s 
a 
? 
e 

6 
4 

J 



K-. 






Milk. 



'Ed 

Cream 



Fig. 2.— Method of reading Babcock test bottles. In reading fat column in milk testing, read from 
a to 6, not a to c, nor a to d. In cream testing, read from a to c, not a to 6, nor a to d. 

The Babcock tester must be run at a definite speed, depending 
upon the diameter of the centrifuge. The proper speed is usually 
indicated on the machine and runs about as follows: 1,000 revolu- 
tions a minute for 12-inch testers, and 800 revolutions for 18-inch 
testers. The samples should be run three times for 5, 2, and 1 
minute periods, respectively. Hot water is added to bring the solu- 
tion up to the neck of the bottle after the 5-minute period. 

The fat column should be clear, with a j-ellow or light-yellow 
color. If the fat colmnn contains white flakes (the result of too 
weak or too httle acid) or black flakes (the result of too strong or 
too much acid), the test must be repeated. 'Before the reading 
is taken the bottles with their columns of fat must be placed in water 
approximating 140° F. (60° C), so that the fat colmnn is smTounded 



16 Department Circular 53, U. S. Dept. of Agriculture. 

by the hot water. They should remain in the bath about 10 minutes 
and be read, one by one, immediately on removal. In measuring 
the fat column in the milk test, read from the bottom to the extreme 
top of the meniscus. In measuring the fat column in the cream 
test, read from the bottom to the lower part of the meniscus. How- 
ever, m the case of cream a more accurate reading can be obtained 
by adding a few drops of glymol to the cream test bottle on removal 
from the water bath. This flattens the meniscus and makes read- 
ing easier. 

SOLroS NOT FAT. 

The solids not fat may be determined by the formula S. N. F.= 
\ L. + .2F, in which ''L" stands for the third and the fourth figures 
of the specific gravity and "F" stands for the percentage of fat. 

Example: Specific gravity at 60° F., 1.032; fat, 4 per cent. 

—^+0.2X4=8.80 solids not fat. 
4 

The following table may be used for estimating the solids not fat: 

Table for determining the solids not fat in milhfrom any given specific gravity and per cent 

offat. 









Lactometer reading at 60° F. 


(Quevenne degrees). 






Per cent 
























of fat. 


























26 


27 


28 


29 


30 


31 


32 


33 


34 


35 


36 


2.00 


6.90 


7.15 


7.40 


7.65 


7.90 


8.15 


8.40 


8.66 


8.91 


.9.16 


9.41 


2.05 


6.91 


7.16 


7.41 


7.66 


7.91 


8.16 


8.41 


8.67 


8.92 


9.17 


9.42 


2.10 


6.92 


7.17 


7.42 


7.67 


7.92 


8.17 


8.42 


8.68 


8.93 


9.18 


9.43 


2.15 


6.93 


7.18 


7.43 


7.68 


7.93 


8.18 


8.43 


8.69 


8.94 


9.19 


9.44 


2.20 


6.94 


7.19 


7.44 


7.69 


7.94 


8.19 


8.44 


8.70 


8.95 


9.20 


9.45 


2.25 


6.95 


7.20 


7.45 


7.70 


7.95 


8.20 


8.45 


8.71 


8.96 


9.21 


9.46 


2.30 


6.96 


7.21 


7.46 


7.71 


7.96 


8.21 


8.46 


8.72 


8.97 


9.22 


9.47 


2.35 


6.97 


7.22 


7.47 


7.72 


7.97 


8.22 


8.47 


8.73 


8.98 


9.23 


9.48 


2.40 


6.98 


7.23 


7.48 


7.73 


7.98 


8.23 


8.48 


8.74 


8.99 


9.24 


9.49 


2.45 


6.99 


7.24 


7.49 


7.74 


7.99 


8.24 


8.49 


8.75 


9.00 


9.25 


9.50 


2. SO 


7.00 


7.25 


7.50 


7.75 


8.00 


8.25 


8.50 


8.76 


9.01 


9.26 


9.51 


2.55 


7.01 


7.26 


7.51 


7.76 


8.01 


8.26 


8.51 


8.77 


9.02 


9.27 


9.52 


2.60 


7.02 


7.27 


7.52 


7.77 


8.02 


8.27 


8.52 


8.78 


9.03 


9.28 


9.53 


2.65 


7.03 


7.28 


7.53 


7.78 


8.03 


8.28 


8.53 


8.79 


9.04 


9.29 


9.54 


2.70 


7.01 


7.29 


7.54 


7.79 


8.04 


8.29 


8.54 


8.80 


9.05 


9.30 


9.55 


2.75 


7.05 


7.30 


7.55 


7.80 


8.05 


8.30 


8.56 


8.81 


9.06 


9.31 


9.56 


2.80 


7.06 


7.31 


7.56 


7.81 


8.06 


8.31 


8.57 


8.82 


9.07 


9.32 


9.57 


2.85 


7.07 


7.32 


7.57 


7.82 


8.07 


8. .32 


8. .58 


8.83 


9.08 


9.33 


9.58 


2.90 


7.08 


7.33 


7.58 


7.83 


8.08 


8.33 


8.59 


8.84 


9.09 


9.34 


9.59 


2.95 


7.09 


7.34 


7.59 


7.84 


8.09 


8.35 


8.60 


8.85 


9.10 


9.35 


9.60 


3.00 


7.10 


7.35 


7.60 


7.85 


8.10 


8.36 


8.61 


8.86 


9.11 


9.36 


9.61 


3.05 


7.11 


7.36 


7.61 


7.86 


8.12 


8.37 


8.62 


8.87 


9.12 


9.37 


9.63 


3.10 


7.12 


7.37 


7.62 


7.87 


8.13 


8.38 


8.63 


8.88 


9.13 


9.38 


9.64 


3.15 


7.13 


7.38 


7.63 


7.88 


8.14 


8.39 


8.64 


8.89 


9.14 


9.40 


9.65 


3.20 


7.14 


7.39 


7.64 


7.89 


8.15 


8.40 


8.65 


8.90 


9.15 


9.41 


9.66 


3.25 


7.15 


7.40 


7.65 


7.91 


8.16 


8.41 


8.66 


8.91 


9.17 


9.42 


9.67 


3.30 


7.16 


7.41 


7.66 


7.92 


8.17 


8.42 


8.67 


8.92 


9.18 


9.43 


9.68 


3.35 


7.17 


7.42 


7.68 


7.93 


8.18 


8.43 


8.68 


8.93 


9.19 


9.44 


9.69 


3.40 


7.18 


7.43 


7.69 


7.94 


8.19 


8.44 


8.69 


8.94 


9.20 


9.45 


9.70 


3.45 


7.19 


7.44 


7.70 


7.95 


8.20 


8.45 


8.70 


8.95 


9.21 


9.46 


9.71 


3.50 


7.20 


7.45 


7.71 


7.96 


8.21 


8.46 


8.71 


8.96 


9.22 


9.47 


9.72 


3.55 


7.21 


7.47 


7.72 


7.97 


8.22 


8.47 


8.72 


8.97 


9.23 


9.48 


9.73 


3.60 


7.22 


7.48 


7.73 


7.98 


8.23 


8.48 


8.73 


8.98 


9.24 


9.49 


9.74 


3.65 


7.23 


7.49 


7.74 


7.99 


8.24 


8.49 


8.74 


8.99 


9.25 


9.50 


9.75 


3.70 


7.24 


7.50 


7.75 


8.00 


8.25 


8.50 


8.75 


9.00 


9.26 


9.51 


9.76 


3.75 


7.25 


7.51 


7.76 


8.01 


8.26 


8.51 


8.76 


9.01 


9.27 


9.52 


9.77 


3.80 


7.26 


7.52 


7.77 


8.02 


8.27 


8.52 


8.77 


9.02 


9.28 


9.53 


9.78 


3.85 


7.27 


7.53 


7.78 


8.03 


8.28 


8.53 


8.78 


9.03 


9.29 


9.54 


9.79 


3.90 


7.28 


7.54 


7.79 


8.04 


8.29 


8.54 


8.79 


9.04 


9.30 


9.55 


9.80 


3.95 


7.29 


7.55 


7.80 


8.05 


8.30 


8. 55 


8.80 


9.05 


9.31 


9. 56 


9.82 



Milk and Cream Contests. 



17 



Table for determining the solids not fat in milk from any given specific gravity aud 

per cent of fat — Continued. 









Lactometer reading at 60° F. 


(Quevenne degrees). 






Per cent 
























of fat. 


























26 


27 


28 


29 


30 


31 


32 

8.81 


33 


34 


35 


30 


4.00 


7.30 


7. 50 


7.81 


8.06 


8.31 


8.56 


9.06 


9.32 


9.57 


9. S3 


4.05 


7.31 


7. 57 


7.S2 


8.07 


8.32 


8.57 


8.82 


9.07 


9.33 


9.-58 


9. S4 


4.10 


7.32 


7. .58 


7.83 


8. 08 


8.33 


8.-58 


8. 8:3 


9.08 


9.34 


9.59 


9.85 


4.15 


7.33 


7. .59 


7. 84 


8.09 


8.34 


8.59 


S. 84 


9.10 


9. 35 


9.61 


9. SO 


4.20 


7.34 


7. 60 


7.85 


8.10 


8.35 


8.60 


8. 85 


9.11 


9.36 


9.62 


9. S7 


4.25 


7.35 


7.61 


7.86 


8.11 


8.36 


8.61 


8.87 


9.12 


9. .37 


9.(53 


9.88 


4.30 


7.36 


7.(i2 


7.87 


8.12 


8.37 


8.62 


8.88 


9.13 


9.38 


9.6-1 


9. 89 


4.35 


7.37 


7. 6.3 


7.88 


8.13 


8.38 


8.63 


8.89 


9.14 


9.39 


9.65 


9.90 


4.40 


7.38 


7. (;4 


7.89 


8.14 


8.39 


8. M 


8.90 


9.15 


9.40 


9. (i6 


9. 91 


4.45 


7.39 


7.65 


7.90 


8.15 


8.40 


8.65 


8.91 


9.16 


9.41 


9.67 


9.92 


4.50 


7.40 


7. 66 


7.91 


8.16 


8.41 


8.66 


8.92 


9.17 


9.42 


9.68 


9. 93 


4. .55 


7.42 


7. 67 


7.92 


8.17* 


8.42 


8.67 


8. 93 


9.18 


9. 43 


9.69 


9.94 


4.60 


7.43 


7.08 


7.93 


8.18 


8.43 


8.68 


8.94 


9.19 


9.40 


9.70 


9. 95 


4. 05 


7.44 


7.69 


7.94 


8.19 


8.44 


8.69 


8.95 


9.20 


9.45 


9.71 


9. 96 


4.70 


7.45 


7.70 


7. 95 


8.20 


8.45 


8.70 


8.96 


9.21 


9.40 


9.72 


9. 97 


4. 75 


7.46 


7.71 


7.96 


8.21 


8.46 


8.71 


8.97 


9.22 


9.47 


9. 73 


9.98 


4. SO 


7.47 


7.72 


7.97 


8.22 


8.47 


8.72 


8.98 


9.23 


9.48 


9.74 


9. 99 


4.85 


7.48 


7.73 


7.98 


8.23 


8.4S 


8.73 


8.99 


9.24 


9.49 


9.75 


10.00 


4.90 


7.49 


7.74 


7.99 


8.24 


8.49 


8.74 


9.00 


9.25 


9.50 


9.76 


10. 01 


4.95 


7.50 


7.75 


8.00 


8.25 


8.50 


8.75 


9.01 


9.26 


9.51 


9.77 


10. 02 


5.00 


7.51 


7.76 


8.01 


8.26 


8.51 


8.76 


9.02 


9.27 


9.52 


9.78 


10. 03 


5.05 


7.52 


7.77 


8.02 


8.27 


8.52 


8.78 


9.03 


9.28 


9.5;j 


9.79 


10. (H 


5.10 


7.53 


7.78 


8.03 


8.28 


8.53 


8.79 


9.04 


9.29 


9.54 


9. SO 


10. 05 


5.15 


7.54 


7.79 


8.04 


8.29 


8.-54 


8.80 


9.05 


9.30 


9.-55 


9. SI 


10. 06 


5.20 


7. .55 


7.80 


8.05 


8.30 


8.-55 


8.81 


9.06 


9.31 


9.-56 


9.S2 


10.07 


5.25 


7.56 


7.81 


8.06 


8.31 


8.56 


8.82 


9.07 


9. ,32 


9. .57 


9.83 


10. OS 


5.30 


7.57 


7.82 


8.07 


8.32 


8.57 


8.83 


9.08 


9.33 


9. -58 


9.84 


10.09 


5.35 


7.58 


7.83 


8.08 


8.33 


8.58 


8.84 


9.09 


9. 35 


9.60 


9. 85 


10. 10 


5.40 


7.59 


7.84 


8.09 


8.34 


8.60 


8.85 


9.10 


9. 36 


9.61 


9. SO 


10.11 


5.45 


7.60 


7.85 


8.10 


8.35 


8.61 


8. 86 


9.11 


9.37 


9.62 


9.87 


10.12 


5.50 


7.61 


7.86 


8.11 


8.36 


8.62 


8.87 


9.12 


9.38 


9.63 


9.88 


10. 13 


5. 55 


7.62 


7.87 


8.12 


8.38 


8.63 


8.88 


9.14 


9.39 


9.64 


9.S9 


10. 14 


5.60 


7.63 


7. 88 


8.13 


8.39 


8.64 


8.89 


9.15 


9.40 


9.65 


9.90 


10. 15 


5.65 


7.64 


7.89 


8.14 


8.40 


8.65 


8.90 


9.16 


9.41 


9. 66 


9.91 


10. 16 


5.70 


7.65 


7.90 


8.15 


8.41 


8.66 


8.91 


9.17 


9.42 


9.67 


9.92 


10. 17 


5.75 


7.66 


7.91 


8.16 


8.42 


8.67 


8.93 


9.18 


9.4;} 


9.68 


9.93 


10.18 


5.80 


7.67 


7.92 


8.17 


8.43 


8.68 


8.94 


9.19 


9.44 


9. 69 


9.94 


10.19 


6.85 


7.68 


7.93 


8.19 


8.44 


8.69 


8.95 


9.20 


9.45 


9.70 


9.95 


10.21 


5.90 


7.69 


7.94 


8.20 


8.45 


8.70 


8. 90 


9.21 


9. 4(; 


9.71 


9.96 


10.22 


5.95 


7.70 


7.95 


8.21 


8.46 


8.71 


8.97 


9.22 


9.47 


9.72 


9.97 


10.23 


6.00 


7.71 


7. 96 


8.22 


8.47 


8.72 


8.98 


9.23 


9.48 


9.73 


9.98 


10.24 


6.05 


7.72 


7.97 


8.2;i 


8.48 


8.73 


8.99 


9.24 


9.49 


9.74 


9.99 


10. 25 


6.10 


7.73 


7.98 


8.24 


8.49 


8.74 


9.00 


9.25 


9.50 


9.75 


10.00 


10. 20 


6.15 


7.74 


7.99 


8.25 


8.50 


8.75 


9.01 


9.26 


9. .51 


9.76 


10.01 


10.27 


6.20 


7.75 


8.00 


8.26 


8.51 


8.76 


9.02 


9.27 


9. .52 


9.77 


10.02 


10.28 


6.25 


7.76 


8.01 


8.27 


8.-52 


8.77 


9.03 


9.28 


9. .53 


9.78 


10.03 


10.29 


6.30 


7.77 


8.02 


8.28 


8.53 


8.78 


9.04 


9.29 


9. .51 


9.79 


10. 04 


10. .30 


6.35 


7.78 


8.03 


8.29 


8.55 


8.79 


9.05 


9.30 


9. .5.5 


9.80 


10.05 


10.31 


6.40 


7.79 


8.04 


8. .30 


8.56 


8.80 


9.00 


9.31 


9. 56 


9.81 


10.06 


10. -32 


6.45 


7.80 


8.05 


8.31 


8. .57 


8. SI 


9.07 


9.32 


9. .57 


9.82 


10.07 


10.33 


6.50 


7.81 


8.06 


8.32 


8.58 


8.82 


9.08 


9. .33 


9. .58 


9.83 


10.08 


10.34 


6.55 


7.82 


8.07 


8.33 


8.-59 


8.83 


9.09 


9.34 


9. .59 


9.84 


10.09 


10. 35 


6.60 


7.83 


8.08 


8.34 


8.60 


8.84 


9.10 


9.35 


9.(K) 


9. 85 


10. 10 


10. 36 


6. (i5 


7.84 


8.09 


8.35 


8.61 


8.85 


9.11 


9.36 


9.61 


9. 86 


10. 11 


10.37 


6.70 


7.85 


8.10 


8. 36 


8.62 


8.86 


9.12 


9. .37 


9. 62 


9.87 


10.12 


10.38 


6.75 


7.86 


8.11 


8. 37 


8.63 


8.87 


9.13 


9.38 


9. (a 


9.88 


10. 13 


10.39 


6. 80 


7.87 


8.12 


8. .38 


8.()4 


8.88 


9.14 


9.39 


9. Of 


9.89 


10.14 


10.40 


6.85 


7.88 


8.13 


8.39 


8.65 


8.89 


9.15 


9.40 


9. 65 


9.90 


10. 15 


10. 41 


6.90 


7.89 


8.14 


8.40 


8. 60 


8.90 


9.16 


9.41 


9. 66 


9.91 


10. 16 


10.42 


0.95 


7.90 


8.15 


8.41 


8.67 


8.91 


9.17 


9.42 


9.67 


9.92 


10.17 


10.43 



PKOPORTION.VL PARTS. 



Lactometer 
fraction. 


Fraction to be 

added 1o solids 

not fat. 


Lactometer 
fraction. 


Fraction to be 

added to solids 

not fat. 


Lactometer 
fraction. 


Fraction to be 

added to solids 

not fat. 


0.1 
.2 

.3 


0.03 
.05 

.08 


0.4 
. .5 

.6 


0.10 
.13 
.15 


0.7 

.8 
.9 


O.IS 
.20 
.23 



18 Department Circular 53, U. S. Dept. of Agriculture. 

Directions for using the table. — If the specific gravity as expressed 
in Quevenne degrees is a whole number, the per cent of solids not 
fat is found at the intersection of the vertical column headed by 
this number, with the horizontal column correspondmg to the per 
cent of fat. If the specific gravity as expressed in Quevenne degrees 
is a whole nimiber and a decimal, the per cent of solids not fat corre- 
spondmg to the whole number is first found, and to that is added 
the fraction fomid opposite the tenth mider ''Proportional parts.'' 
Two examples may suffice for illustration: (1) Fat, 3.8 per cent; 
specific gravity, 1.0320. Under column headed 32, 8.77 per cent is 
found corresponding to 3.8 per cent fat. (2) Fat, 3.8 per cent; 
specific gravity, 1.0325. The per cent of solids not fat corresponding 




Fig. 3.— Determination of acidity. 



to this per cent of fat and a specific gravity of 32 is 8.77. Under 
"Proportional parts" the fraction appearing opposite 0.5 is 0.13, 
which, added to 8.77, makes 8.90, the desired per cent. 



AcroiTY. 



In order to obtain comparable results, it is best to follow strictly 
the method given in leaflet A 12, previously mentioned. The milk 
must not be diluted with water, as that causes a perceptible error 
in the results. Fifty cubic centimeters of milk or cream are taken, 
and titrated against a tenth-normal sodiiun-hydroxid solution, using 
phenolphthalein as indicator. Care must be taken near the end of 



Milk and Cream Contests. 



19 



the titration in. order to develop a faint pink color over the entire 
surface of the milk. The pink color disappears on standing for a 
short time. The calculation is as follows: 

T, * f •!•* cc NaOHn/LOx. 009x100 

Per cent of ariditv= ~ 

50 

The following table gives the acidity when 50 cubic centimeters of 
m.ilk are titrated against tenth-normal alkali: 

Determinalion of acidity in milk. 



Cubic cen- 


Ter cent 


Cubic cen- 


Per cent 


Cubic cen- 


Per cent 


Cubic cen- 


Per cent 


timeters 


acidity as 


timeters 


acidity as 


timeters 


acidity as 


timeters 


acidity as 


NaOHn/10. 


lactic acid. 


NaOH n/10. 


lactic acid. 


NaOH n/10. 


lactic acid. 


NaUH n/10. 


lactic acid. 


4.0 


0.072 


7.5 


0. 135 


11.0 


0.198 


14.5 


0.261 


4.5 


.081 


8.0 


.144 


11.5 


.207 


15.0 


.270 


5.0 


.090 


8.5 


.153 


12.0 


.216 


15.5 


.279 


5.5 


.099 


9.0 


.162 


12.5 


.225 


16.0 


.288 


6.0 


.108 


9.5 


.171 


13.0 


.234 


16.5 


.297 


6.5 


.117 


10.0 


.180 


13. 5 


.243 


17.0 


.306 


7.0 


.126 


10.5 


.189 


14.0 


.2.52 


17.5 


.315 



SEDIMENT. 



The sediment in milk may be determined by means of some form 
of sediment tester or by observing the bottom of the milk in the 
bottle. If the sediment tester is used the pint sample of milk should 




Ffg. 4.— Sediment testers. 

be warmed slightly before being run through the tester, since cold 
milk runs tln-ough slowly. At the completion of the test the resulting 
cotton disks are gi^ouped according to the quantity of sediment shown. 
A perfectly clean cotton scores 10. Figure 5 shows a method of 
grouping with numerical rating. ^Yhile the numbers in the figure 
show a half-point difference only, the analyst can make ratmgs be- 
tween these numbers. For example, a cotton disk showing less dirt 
than 8, but more than 8.5, can be given a rating between 8 and 8.5. 



20 Department Circular 53, U. S. Dept. of Agriculture. 







.a 
3 

3 



!3 

3 



a 
a 

a 



C3 

-a 
a 

53 



"3 

6 

I— I 
fr4 



Milk and Cream Contests. 21 

Care must be taken to rinse out the tester after each sample lias been 
run through. 

It is inadvisable to use the sediment tester for cream, for on account 
of its heavy viscosity cream may clog the tester entu-ely. Particles 
of fat may also obscure any sediment. Sediment in cream should 
therefore be judged in the bottle. Before scoring, the bottles should 
be allowed to stand undisturbed for at least an hour to allow any 
sediment to settle. Then the bottle should be raised carefully, tip- 
ping only slightly, so that the bottom can be observed. To score 
perfect, not so much as a movable speck must be visible in the bottom 
of the bottle. When sediment is present, points must be deducted 
according to the quantity. 

Tliis bottle method mav be used in the same manner for testing 
the sediment in milk, and the grading shown in figure 5 applies equally 
in determining the score. 

FLAVOR AND ODOR. 

The most common ''off flavors" and odors found in milk and 
cream are those produced by certain feeds; by the absorption of foul 
odors from the stable; and from the presence of foreign substances 
in the milk. Before scoring, the samples should be set in warm water 
to warm the milk and cream slightly. Tlie scoring must be done in 
a room free from odors. The sample of milk or cream should be well 
mixed before the cap is removed, then about half the contents of the 
bottle should be poured into a clean beaker. Any odor present can 
be detected by placing the nose over the mouth of the bottle, and the 
flavor is judged by taking a little of the product into the mouth. It 
is not advisable to swallow the liquid if many samples are to be scored, 
since it tends to reduce the sensitiveness of taste. If the flavor is 
very bad it can usually be definitely classified. Points are deducted 
for flavors resulting from strong feeds, and for c-owj, strong, bitter, 
sour, or other ofl^ flavors. 

BOTTLE AND CAP. 

Regulation milk bottles must be used in milk and cream contests 
and they should be completely filled so that there will be no churn- 
ing. Deductions in the score are made for dirty or chipped bottles 
and for caps which do not cover the lips of the bottles or which do 
not fit properly in the cap seats. To obtain a perfect score the top 
of the bottle nmst be covered with parchment paper, metal foil, or 
some other cover impervious to water and dust. 

TEMPERATURE. 

In contests where the samples are taken on the street, the tempera- 
ture of the milk must be recorded at the time the sample is collected, 
but the sample used for ascertaining temperature must not be taken 



22 Department Circular 53, U. S. Dept. of Agriculture. 

for bacterial count. The inspector by previous experiments must 
determine how long it takes for the mercury in the tube to become 
stationary and must leave the thermometer bulb in the milk until 
the mercury has registered the correct temperature. The thermom- 
eter should be read, of course, while the bulb is in contact with the 
milk. Only an accurate thermometer must be used, and care must 
be taken to prevent breaks in the mercury column. Should such 
breaks occur they can be corrected by grasping the thermometer in 
the hand, bulb down, and giving it a long outward sweep, or by placing 
the bulb in hot water until the mercury has miited. 

BACTERIAL COUNT. 

In the determination of bacteria, the standard methods of bacte- 
riological analysis of milk should be followed. Special care should 
be taken in the sterilization of glassware and of dilution bottles, and 
in the preparation of media. Whenever passible thi-ee plates should 
be made. In a contest with prepared samples, the following plates 



' ^Wm 


«» 




^ 


^"-^^ 


"# •- 










, i 



Fig. 6.— Bottles with protective coveriags. 



are recommended; Two of ^wo, and one of ^ ^q q . In a contest with 
street samples it is well to vary this somewhat; as, for example, one 
of YD-oj aiid two of Yow^; or two of y^> ^^^^ ^^^ ^^ loooo * 111- the 
latter case, however, the analyst will know from his own experience 
just what dilutions to make. 

A blank contaming media and dilution water should be run side by 
side with the regular samples. Plates must not be poured until the 
temperature of the melted media averages between 106° and 113° F. 
(41° and 45° C). The plates must be left in the incubator for 48 
hours, and the temperature of the incubator should be kept at about 
100° F. (37.5° C). For counting colonies, a counting plate and a 
reading glass magnifymg 2^ diameters should be used, and in report- 
ing the counts the standard methods should be strictly followed. 

In cities where the continuous contest is in operation, and where 
the results are averaged every 3, 6, or 12 months, there will be from 
4 to 24 bacterial counts to average. It is generally conceded that the 
arithmetical average may give results which are too high, especially 



Milk and Cream Contests. 



23 



when one of the counts is much higher than the others. On that ac- 
count the followmg table of per cent ratings has been prepared, the 
use of which, it is thought, will give a fair average of bacteria in 
counts of 4 or more. Briefly, the method consists in arranging the 
ratings and not the bacterial counts, and is more fully explained by 
an example following the table: 

Per cent ratings for various bacterial counts. 



Bacteria per 




Bacteria per 




Bacteria per 




Bacteria per 




cubic 


Rating. 


cubic 


Rating. 


cubic 


Ratuig. 


cubic 


Rating. 


centimeter. 




centimeter. 




centimeter. 




centimeter. 






Per cent. 




Percent. 




Per cent. 




Per cent. 





100.0 


28,000 


76.3 


66.000 


63.4 


140,000 


47.0 


500 


99.0 


29,000 


75.9 


67,000 


63.1 


150,000 


45.1 


1,000 


97.2 


30,000 


75.5 


68,000 


62.9 


160,000 


43.3 


1,500 


96.0 


31,000 


75.1 


69,000 


62.6 


170,000 


41.5 


2,000 


94.6 


32,000 


74.6 


70,000 


62.4 


180,000 


39.8 


2,500 


93.8 


.33,000 


74.2 


71,000 


62.1 


190,000 


38.2 


3,000 


93.0 


3 J, 000 


73.9 


72,000 


61.9 


200, 000 


36.6 


3,500 


92.2 


35,000 


73.5 


73,000 


61.6 


210,000 


35. 1 


4,000 


91.2 


.36,000 


73.1 


74,000 


61,4 


220,000 


33.6 


4,500 


90.8 


37,000 


72.8 


75,000 


61.1 


230,000 


32.1 


5,000 


90.2 


38,000 


72.4 


76,000 


60.8 


240,000 


30.6 


5,500 


89.6 


39,000 


72.0 


77,000 


60.6 


250,000 


29.2 


6,000 


89.0 


40,000 


71.6 


78,000 


60.3 


2{i0,000 


27.8 


6,500 


88.6 


41,000 


71.3 


79,000 


60.0 


270,000 


26.5 


7,000 


88.2 


42,000 


70.9 


80,000 


59.8 


280,000 


25.2 


7,500 


87.6 


43,000 


70.6 


81,000 


59.6 


290,000 


23.8 


8,000 


87.2 


44,000 


70.2 


82,000 


59.3 


300,000 


22.4 


8,500 


86.8 


45,000 


69.9 


83,000 


59.1 


310,000 


21.2 


9,000 


86.4 


46,000 


69.6 


84,000 


58.8 


320,000 


20.0 


9,500 


86.0 


47,000 


69.2 


85,000 


58.6 


330,000 


18.8 


10,000 


85.6 


18,000 


68.9 


86,000 


58.3 


340,000 


17.4 


11,000 


85.0 


49,000 


68.6 


87,000 


58.1 


350,000 


16.2 


12,000 


84.4 


50,000 


68.3 


88,000 


57.8 


360,000 


15.0 


13,000 


83.8 


51,000 


68.0 


89,000 


57.6 


370,000 


13.8 


14,000 


83.2 


52,000 


67.6 


90,000 


57.4 


380,000 


12.6 


15,000 


82.6 


53,000 


67.3 


91,000 


57.2 


390,000 


11.5 


16,000 


82.0 


54,000 


67.0 


92,000 


56.9 


400,000 


10.4 


17,000 


81.4 


55,000 


66.7 


93,000 


56.7 


410,000 


9.4 


18,000 


81.0 


56,000 


66.3 


94,000 


56.4 


420.000 


8.2 


19,000 


80.4 


57,000 


66.0 


95,000 


56.2 


430,000 


7.2 


20,000 


80.0 


5'<,000 


65.7 


96,000 


56.0 


440,000 


6.2 


21,000 


79.4 


59,000 


65. J 


97,000 


55.8 


450,000 


5.2 


22,000 


79.0 


60,000 


65.2 


98,000 


55.6 


460,000 


4.0 


23,000 


78.6 


61,000 


64.9 


99,000 


55. 4 


470,000 


3.0 


24,000 


78.2 


62,000 


64.6 


100,000 


5.5.1 


480,000 


2.0 


25,000 


77.6 


(>3,0CH) 


64.3 


110,000 


53.0 


490,000 


1.0 


26,000 


77.2 


64,000 


64.0 


120.000 


50.8 


5(X).000 


0.0 


27.000 


76. S 


65.000 


63.7 


130. onn 


48.8 







The bacterial average is determined thus: Suppose the following 
bacterial counts are the result of five counts from samples taken from 
dairyman "A": 11,000, 65,000, 80,000, 18,000, 450,000. Tliese are 
arranged in order with their corresponding per cent ratings taken 
from the table. The ratings are then added and divided by the 
number of samples. 



Bacteria counts. 

11,000 
65,000 
80,000 
18,000 
450,000 



Per cent ratings. 

85. 
63.7 
.59.8 
81.0 
5.2 

5 )294.7 
.58.9 



24 Department Circular 53, 11. S. Dept. of Agriculture. 

The average per cent rating is 58.9. By consulting the table it is 

found that the rating closest to 58.9 is 58.8; therefore the average 

bacteria count for samples from A's dairy is 84,000. By contrast it 

may be noted that the arithmetical average of the bacterial counts 

would be 125,000. 

PUBLICITY. 

Proper publicity has a valuable place in promoting milk and cream 
contests. It is not only necessary to give newspaper publicity 
to prepared contests, but the results of all contests should be an- 
nounced in a popular, readable way. In prepared contests the names 
of the winners of each class, with their scores and the prizes won, 
should always be given. In the continuous contest, when the results 
are announced at definite periods of time, the winners of prizes with 
their scores may be given. It is thought advisable, however, in con- 
tinuous contests to group the dairymen in classes, as A, B, and C, 
and publish these groupings. For instance, all the dahymen scoring 
between 90 and 100 could be placed in Class A, those scoring between 
80 and 90 in Class B, etc. 

In connection with the announcement of winners in contests where 
the samples are taken on the street, it is advisable to arrange a meet- 
ing of producers to discuss in a practical way methods for producing 
better milk. Consumers may also be interested, not only in pub- 
hcity but by meetings at which milk questions of interest to them 
are discussed. 



LIBRARY OF CONGRESS 

III I iiili iiil iSi'll iii'il fill! I!l!' ! 'I <■■>■ iiiJi ■iiHiii 





000 895 572 4 % 



m: 



omaer 

Gaylord Bros. Inc. 

Makers 
Syracuse, N. Y. 

PAT. JAN 21, I30B 




